1. Field of the Invention
The present invention relates to photoelectrophoretic imaging and more particularly to configurations and procedures for use in photoelectrophoretic imaging to provide duplex copy sheets (i.e. copies which have images on both sides of the sheet).
2. Description of Prior Art
Photoelectrophoretic imaging involves the exposure of a suspension, containing electrophotosensitive marking particles in a carrier liquid, to a light image while in the presence of a migration inducing electrical field (usually provided by sandwiching electrodes). In response to the imaging exposure, particles within the suspension migrate to form corresponding image patterns on the electrode surfaces (e.g. a negative sense image on what has been termed an "injecting" electrode and a positive sense image on what has been termed a "blocking" electrode). In the usual imaging technique the desired image is transferred from its electrode to a receiver sheet and fixed by heating and/or pressure. For color imaging the suspension contains different color particles (with respectively different electrophotosensitivities) and the exposing image is a color negative or positive.
The most common configuration proposed for automated photoelectrophoretic imaging involves opposed cylindrical electrodes forming an imaging nip where a light image is strip scanned onto suspension within the nip in synchronization with the rotation of the cylindrical electrodes. The desired image is transferred to a receiver at a location downstream from the imaging nip. In some configurations (usually in neg.-pos. imaging) a receiver is attached to one electrode (usually the blocking electrode); and the image is formed directly on the receiver, which is subsequently separated from the electrode.
For certain applications, e.g. brochures and advertising literature, it is desirable to provide images on both sides of a copy sheet, i.e. duplex copy sheets.